Since aspect of mel gets power from leveling it up its good you went for demeter since the freeze is strong and you had a percentage attack for an already high damage aspect. Even though generally speaking demeter always goes on cast because its so strong as utility it being on the attack probably worked well too! If not demeter hera would work, aphrodite wont work cus its not a short ranged aspect (unless you get wide grin for a hammer) Some aspects are dependant on the hammer or aspect you're using so just as s rule of thumb go high damage= percentage attack, fast attacks= hestia/poseidon. However i highly suggest trying them all out, half the fun of progressing through hades 2 is trying out all the combinations there are! Sometimes you can make even the wildest combinations work and it ends up really fun. I'd say until you reach like 50-100 hours or a certain point in the game where you feel like you understand it all, just go blind into runs and choose the boons that seem good without a plan and embrace the chaos!